Relationship between serum leptin and fatty liver in Japanese male adolescent university students

OBJECTIVE: The aim of this study was to elucidate the relationship between serum leptin levels and fatty liver in male adolescents. METHODS: We investigated the relationship between the concentration of circulating leptin and fatty liver by measuring the serum concentration of leptin in 284 male students who received the matriculation health examination in Okayama University in 1996 (n = 197; age, 18-20 yr) or 1997 (n = 87; age, 18-20 yr). RESULTS: Serum leptin levels correlated positively with body mass index (BMI), percent body fat (%FAT), thickness of skin fold (TSF), and serum concentration of ALT in 197 subjects. Examination of serum leptin in 67 subjects with BMI ≥24.2 but <28.6 kg/m² showed a progressively higher levels in subjects with high serum ALT. Serum leptin levels in subjects with abnormally high serum ALT (≥37 IU/L) were significantly higher (p < 0.05) than in subjects with normal serum ALT, independent of BMI, %FAT, and TSF. Serum leptin levels were also significantly higher in subjects with fatty liver (detected by abdominal ultrasonography), independent of BMI and %FAT, compared with subjects without fatty liver. Stepwise multiple regression analysis showed that serum leptin level was an independent risk factor for fatty liver. In addition, serum leptin levels correlated with serum ALT (r = 0.518; p < 0.0005) and cholinesterase (r = 0.511; p < 0.0005) levels in 48 subjects with fatty liver. CONCLUSIONS: Our results demonstrated that serum leptin concentrations are high in male adolescents with simple obesity and are associated with high serum ALT or fatty liver, independent of BMI and %FAT, suggesting that the concentration of circulating leptin correlates with fatty liver caused by accumulation of visceral fat.